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Mar 8, 2018

See below.

#### Explanation:

Imposing a vertical acceleration on ${m}_{A}$ as a consequence, due to kinematic restrictions, we have

${a}_{2}^{2} = {a}_{x}^{2} + {a}_{1}^{2}$

with

${a}_{1} / {a}_{x} = \tan \theta$

hence

${a}_{2}^{2} = {a}_{1}^{2} / {\sin}^{2} \left(\theta\right)$